A pharmaceutical container typically includes an open-ended vial which is filled with a medicinal composition. The vial typically is sealed with a closure member in the shape of an open-ended cylindrical cup having a base and walls extending vertically therefrom, i.e., a shell cap. The shell cap aids in preventing contamination of the composition within the vial.
Manufacture of shell caps for use in pharmaceutical containers entails punching preforms from a sheet of lacquered metal such as aluminum, and subsequently shaping those preforms into shell caps. Often, the metal sheet is lacquered on only a single surface. During these punching and forming operations, the lacquer coating is broken whereby the resulting shell caps have bare metal surfaces and edges. These bare metal surfaces and edges of the shell caps generate metal particulates when the shell caps contact each other or other objects such as during transport of the caps. In addition, lacquer particles can be produced when the shell caps contact each other or other objects such as during transport of the caps.
Various processes for coating and protecting bare metal portions of containers have been proposed. For example, U.S. Pat. No. 4,451,506 shows coating the bare metal edges of a can blank with a polyamide adhesive tape. This method, however, cannot be employed practically if the metal is exposed to high temperatures as would be incurred during sterilization by autoclaving. Substituting plastic for metal also would not be acceptable since many plastics are not capable of dimensionally withstanding temperatures associated with autoclaving.
The presence of metal and lacquer particulate impurities is of special concern since the particulates can adhere to various portions of the shell cap. As a result, when the shell caps are washed prior to assembly to the vials, particulates on the shell caps can contaminate the pharmaceutical washing machines and thereby other components which might be washed in those machines. It also is important to prevent these particulate impurities from contaminating the medicinal compositions in the pharmaceutical container. A need therefore exists for minimizing the formation of particulates during the manufacture of pharmaceutical containers and closure members.